1. Field of the Invention
This invention relates to a method for removing waste materials from water. More particularly, this invention relates to a new use for spent ion exchange resins such as, for example, the type used in MTBE production, to remove alkaline materials from contaminated water. This method is not only inexpensive and efficient, but also reduces problems inherent in disposal of the partially depleted catalyst and would reduce the impact on the environment of contaminants and old catalysts.
2. Description of Related Art
The use of ion exchange resins for removal of magnesium and noncarbonate minerals from water is known in the field of water treatment or water softening. The cost and frequency of regeneration are principal disadvantages. The ion-exchange materials generally used in softening water are styrene-divinyl benzene copolymers. Kirk-Othmer Encyclopedia of Chemical Technology, 8, 70 and 24, 425 (1982).
It is known in the art that morpholine may be removed from aqueous solutions with ion exchange resins. Such a method is described in Khim Prom (Moscow) 1983, pp. 83-83. The disadvantage is the high cost of the resin. A variation on the Russian technique is described in U.S. Pat. No. 5,043,075 where the cation exchange resin contains carboxyl groups instead of the conventional sulfonic acid groups.
Morpholine is an industrially useful amine because of its qualities as a corrosion inhibitor in boiler water. It is used in the preparation of many chemicals, drugs and pesticides and consequently, it can be found in many industrial effluents. Studies on the biodegradability of morpholine are summarized in a paper by J. S. Knapp et al., Journal of Applied Bacteriology, 1982, 52, 5-13. It was found that under controlled conditions morpholine is completely biodegradable.
One of the most critical areas of study in industrial chemical processes is that of devising methods to remove impurities from waste water at low cost, and another is searching for ways to avoid having to dispose of chemical compositions such as catalysts which are still partially active. Plants producing or using basic materials such as ammonia, organic amines, alkali salts or caustic have waste streams that often need to be neutralized.
Waste water streams pose a problem for disposal because many of the amines and metals are toxic. In dilute solutions, distillations and extraction methods are prohibitively expensive. A method often used for ridding waste water of amine products is burning the amine streams. Actually, this method is fairly expensive as well. The cost can run as high as $2.00/gallon.
Another aspect of the background for this invention is that the current transition to unleaded fuels in the United States has caused a demand for the addition of oxygenates into gasoline which has lead to the development of methyl-tert-butylether (MTBE) as a gasoline additive. MTBE and other chemicals such as ethyl-tert-butylether (ETBE) and tert-amyl methylether (TAME) are made by the addition of alcohol to an olefin catalyzed by a sulfonic acid ion exchange resin. The demand for MTBE has caused it to be the fastest growing chemical of the 80's and the demand will grow rapidly in the 90's. Chemical Business, January 1992, p. 24.
The consumption of MTBE is currently about 180,000 barrels per day and could be as high as 670,000 barrels per day by the year 2000. Ibid, p. 25. Another reference indicates the demand would reach 1.2 million barrels per day by the year 2000. (Chemical Week, Nov. 20, 1991, p. 36.)
Due to the demand for high productivity in the production of MTBE the ion exchange catalyst is used until reduced activity makes it more reasonable to exchange it for a fresh catalyst. This corresponds to a point of about 70-80% of its original activity. This means there are enormous amounts of used catalyst that must be disposed of. Disposal of this partially spent catalyst gives rise to environmental concerns and often requires some type of permit. It would be extremely efficient from a commercial and environmental viewpoint to accomplish a desirable goal using this partially spent catalyst and, at the same time, reduce the remaining activity of the resin so that disposal of it is not as objectionable.
It would be a distinct advance in the art if an inexpensive means were available for removing alkaline impurities from waste water. It would be extremely efficient and advantageous if this could be accomplished with a substance which to this point has had to be discarded due to the productivity requirements in the MTBE, ETBE or TAME synthesis reaction. To remove impurities from waste water in one process with a partially spent catalyst that normally entails disposal problems would be quite efficient in every respect.